- The SLD (single line diagram) is a one-line drawing of the whole solar system.
- It shows the array, DC side, inverter, isolators, earthing, net meter and grid tie-in.
- The DISCOM uses it to confirm the system is wired safely before sanction.
- Format and the signing licence class vary by DISCOM — verify.
- The SLD must match the equipment actually installed, or it is rejected.
The solar SLD for net metering is a small drawing with big power: it can clear an application or stall it. A single line diagram shows the whole electrical system on one line, from the panels to the grid. The DISCOM reads it to confirm the system is safe and correct before sanctioning net metering. This guide breaks down every component it must show.
What a single line diagram is
A single line diagram is a simplified electrical drawing that shows the system as one line, even where there are several wires. It maps the path of power from the solar array, through the inverter and protection devices, to the net meter and the grid connection. It is the standard way engineers describe an electrical layout clearly.
For net metering, the SLD is part of the application. It tells the DISCOM what you are connecting and how it is protected. A clear, correct SLD signals a clean install; a messy or wrong one invites questions and delay.
SLD vs layout drawing
An SLD is not a physical layout. It does not show where things sit on the roof. It shows the electrical relationships — what connects to what, in what order, with what protection. Some DISCOMs also ask for a layout or location plan separately.
Why the DISCOM needs the SLD
The DISCOM needs the SLD to confirm your system is wired safely and meets the connection rules before it allows power onto the grid. The drawing lets the DISCOM engineer check the inverter, the isolation devices, the earthing and the metering point without visiting the site first. It is the safety review on paper.
It protects the grid and the people on it
The SLD shows the isolators and anti-islanding inverter that keep the system from energising a dead line. The DISCOM verifies these before sanction because the safety of line workers depends on them. The SLD is where that protection is documented.
SLD component breakdown
Every net-metering SLD is built from the same core blocks, in order from the array to the grid. The table below breaks down each component, what to show, and why it is there. The exact items a DISCOM requires can vary, so confirm the local checklist.
Shows generation source and size
Safe DC collection up to the inverter
The grid-tied converter with anti-islanding
Manual disconnect for safety
Protective and system earthing
Records import and export
Where the system meets the grid
Required components vary by DISCOM — verify the local checklist.
The inverter on the SLD must match the approved inverter standards, and the earthing and isolators must match CEA safety compliance. The SLD is where all of it comes together on one page.
DISCOM format and signing rules
The SLD format and the signature it needs are set by the DISCOM, so verify them for your state. Many DISCOMs publish their own template. Most require the drawing to be signed by a licensed electrical engineer or contractor of an accepted class, especially for larger commercial systems. Using the right format and signatory the first time avoids a return.
Who signs it
The signing engineer vouches that the design is safe and correct. The licence class the DISCOM accepts can depend on the system size and voltage. For larger systems, this links to the electrical inspector approval as well, which we cover in the CEIG / electrical inspector guide.
How current flows on the SLD
Reading the SLD left to right (or top to bottom) follows the power. Understanding the flow helps you draw it correctly and explain it to a DISCOM engineer.
- Array → DC isolator — DC power leaves the panels and passes a DC disconnect and protection.
- DC isolator → inverter — the inverter converts DC to grid-quality AC, with anti-islanding built in.
- Inverter → AC isolator/breaker — the AC side gets its own disconnect for safety.
- AC → net meter — power passes the bidirectional meter that records import and export.
- Net meter → point of connection — the system ties into the DISCOM supply.
- Earthing — connected throughout for protection.
On a three-phase service the same flow applies across three phases, which is why the inverter and meter type must match the connection — see single-phase vs three-phase.
Why an SLD gets rejected
Most SLD rejections come from a handful of avoidable issues. Check these before you submit.
- Missing components — no isolator, no earthing, or no clear metering point.
- Equipment mismatch — the SLD shows a different inverter or meter than installed.
- Wrong format — not the DISCOM's template, so the reviewer cannot check it quickly.
- No valid signature — unsigned, or signed by the wrong licence class.
- Unclear ratings — missing kWp, inverter rating or cable sizes.
An SLD that matches the installed system, in the DISCOM format, with the right signature, clears most checks. For the wider list of stall reasons, see why a feasibility request is rejected.
Drawing the SLD right the first time
Build the SLD from the actual equipment list, not a generic template. Pull the inverter make and rating, the meter type, the isolator ratings and the earthing details from the real design. Then fit them into the DISCOM's format and get the right engineer to sign.
Keep it consistent with the documents
The SLD should agree with the rest of the net-metering document set — the system size, the inverter, the meter and the sanctioned load. A mismatch between the SLD and the application is a common reason for a query. One source of truth for the design prevents that.
Label everything clearly
A reviewer should be able to read the SLD without guessing. Label the array size in kWp, the inverter make, model and rating, the meter type, the isolator and breaker ratings, and the cable sizes. Mark the point of connection and the earthing clearly. Unlabelled or vague symbols slow the review and invite questions. Clean labelling signals a professional install and speeds the sign-off.
As-built vs proposed SLD
Some DISCOMs accept a proposed SLD at application and expect an as-built SLD after installation. If the install differs from the proposal — a different inverter model, a changed string layout — the as-built drawing must reflect reality. Submitting an as-built that still shows the old design is a common slip. Update the SLD whenever the equipment or layout changes, so the final drawing matches what is actually on the roof.
Reuse a clean template across jobs
Once you have an SLD that a DISCOM has accepted, turn it into a template for similar systems on that DISCOM. Keep the structure, swap the equipment ratings, and refresh the signature. This cuts drawing time and reduces the chance of leaving out a required component. Maintain one template per DISCOM format, because the requirements differ, and keep each in step with the latest published checklist.
How SuryaHub helps you keep the SLD clean
An SLD is only as good as the design data behind it, and SuryaHub keeps that data straight. SuryaHub holds the equipment list, system size and document set on each project in project management, and runs the application through the DISCOM workflow, so the SLD matches the installed system and the right files reach the DISCOM together. SuryaHub is pre-revenue; the real pilots are Suryantra Energy and RGESPL, and every figure here is a scheme or technical fact, not a guarantee.
One source of truth for every drawing
See how SuryaHub keeps the SLD and documents matched to the install.
Related guides
Frequently asked questions
What is a single line diagram (SLD) for net metering?+
A single line diagram for net metering is a one-line electrical drawing of the solar system, from the PV array through the inverter and protection devices to the net meter and the grid connection. The DISCOM uses it to confirm the system is wired safely and correctly before it sanctions net metering.
What must an SLD for net metering show?+
An SLD for net metering must show the PV array and size, the DC side with isolator and protection, the inverter make and rating, the AC isolator or breaker, earthing, the bidirectional net meter, and the point of connection to the grid. The exact items required vary by DISCOM, so verify the local checklist.
Who signs the SLD for net metering?+
The SLD for net metering is usually signed by a licensed electrical engineer or contractor whose class the DISCOM accepts. The signing and licence-class requirement varies by DISCOM and state, so confirm the accepted signatory before you submit, especially for larger commercial systems.
Why does the DISCOM reject an SLD?+
The DISCOM rejects an SLD when it misses required components, shows the wrong inverter or meter, omits the isolator or earthing, uses a non-standard format, or lacks the required signature. Matching the system on the SLD to the equipment actually installed, in the DISCOM format, avoids most rejections.
Is the SLD format the same for every DISCOM?+
No. The SLD format is not the same for every DISCOM. Many DISCOMs publish their own template and signing rules. Treat any sample SLD as a guide, and verify the format, the required components and the signatory against your target-state DISCOM checklist before you submit it.
How does SuryaHub help with the SLD and documents?+
SuryaHub keeps the design, equipment list and document set on each project, so the SLD matches the installed system and the right files reach the DISCOM. SuryaHub is pre-revenue; the real pilots are Suryantra Energy and RGESPL.
Sources & references
The safety and connectivity items shown on the SLD come from CEA standards and the Rights of Consumers Rules, with the drawing format set by each DISCOM. Confirm the format and signatory with your DISCOM before you submit.
- Central Electricity Authority (CEA) ↗
Technical and safety standards for grid-connected systems shown on the SLD.
- Ministry of Power ↗
Electricity (Rights of Consumers) Rules — connection and metering.
- Ministry of New & Renewable Energy (MNRE) ↗
Rooftop solar programme guidelines applied by DISCOMs.
Written by the SuryaHub team · reviewed against CEA, MoP & DISCOM sources · updated 19 June 2026.
Method: SLD content rules are taken from CEA and DISCOM sources above and re-checked every 30 days. SLD format and signing requirements are DISCOM-specific and must be verified. SuryaHub is pre-revenue; only Suryantra Energy and RGESPL are real pilots.
Change log: 19 Jun 2026 — first published.